fixed a failing test caused by the change in verbiage to AMQPConnectionError
fixed failing test caused by Channel.close being
updated to call basic_cancel with  kwarg
Fixed an issue with calling `Channel.basic_cancel` and then `Channel.close`.
`Channel.close` set the channel state to `CLOSING`, and then proceeded to
call `basic_cancel` for all current consumers which checks that the
channel is open and raises a `ChannelClosed` exception if it isn't. I
just deleted the state change from `close` as it still gets set to
`CLOSING` in `_shutdown`.
Merge pull request #256 from atatsu/basic_cancel-fix

Channel.close() fix when there are consumers